%0 Journal Article
%T A Simplified Formulation for Rough Surface Cross-Polarized Backscattering Under the Second-Order Small-Slope Approximation
%+ Institut méditerranéen d'océanologie (MIO)
%+ Department of Computer Science and Engineering [Columbus] (CSE)
%A Guérin, Charles-Antoine
%A Johnson, Joel T.
%< avec comité de lecture
%@ 0196-2892
%J IEEE Transactions on Geoscience and Remote Sensing
%I Institute of Electrical and Electronics Engineers
%V 53
%N 11
%P 6308-6314
%8 2015
%D 2015
%R 10.1109/TGRS.2015.2440443
%K Wind speed
%K Rough surfaces
%K Sea surface
%K Surface roughness
%K Cross-polarization
%K Approximation methods
%K Backscatter
%K Kernel
%K microwave remote sensing
%K sea surface scattering.
%Z Sciences of the Universe [physics]/Ocean, AtmosphereJournal articles
%X We present simplified expressions for the cross-polarized backscatter of a randomly rough surface predicted by the second-order small-slope approximation (SSA2). The simplification is based on appropriate polynomial approximations of the SSA2 kernel function. We obtain numerically efficient expressions for the cross-polarized backscattering amplitude of a deterministic surface in the form of a single space integral involving only the surface elevation and the second (mixed) derivative of the surface elevation. The ensemble average normalized radar cross section is then derived under a Gaussian random process assumption for the surface. The resulting expression has the form of a Kirchhoff integral involving the roughness correlation function and its second- and fourth-order cross-derivatives. Further simplification is achieved for off-nadir observations using a high-frequency approximation; the result is an analytical formula involving only the resonant curvature and the radar-filtered mean square slope in the out-of-plane direction. A numerical validation of the simplified expressions is provided by comparison with exact SSA2 predictions in representative test cases. The dependence of cross-polarized backscattering on the incidence angle as well as wind speed and direction is then investigated for the case of a directional sea surface model. At near nadir incidence, a clear maximum in azimuth of the cross-polarized backscatter is observed for radar look directions 45° from the wind direction.
%G English
%2 https://hal.archives-ouvertes.fr/hal-01171571/document
%2 https://hal.archives-ouvertes.fr/hal-01171571/file/Simplified.pdf
%L hal-01171571
%U https://hal.archives-ouvertes.fr/hal-01171571
%~ CNRS
%~ UNIV-TLN
%~ OSU-INSTITUT-PYTHEAS
%~ IRD
%~ UNIV-AMU
%~ GIP-BE
%~ MIO
%~ TEST-AMU